Most side effects of an epidural steroid injection are transient and expected. A small number are emergencies, and knowing which is which is the point of this guide.
The material here follows the complication teaching of Dr. María Alejandra De La Peña, an anaesthesiologist fellowship-trained in interventional pain management at Harvard Medical School's Beth Israel Deaconess Medical Center.
Common and self-limiting
These are described by faculty as routine rather than as complications:
- Post-procedure pain. An increase in the original pain as local anaesthetic wears off. Managed with ice, NSAIDs or a muscle relaxant, and with reassurance — De La Peña frames explaining it as part of the treatment.
- Contrast rash. An allergic reaction to contrast producing a rash, which she notes is “quite common”.
- Facial flushing and hiccups. Steroid effects, lasting a day or two.
- Transient rise in blood pressure.
- Anxiety and insomnia for a night or two.
- Vasovagal syncope — common, and more so in “strong young patients” who are nervous. Treated with supine positioning, knees bent, fluids and reassurance.
Raised blood glucose, and why it lasts longer than people expect
This deserves its own section because it is predictable, it is manageable, and it is routinely under-communicated.
Epidural steroid causes rebound hyperglycaemia for several days. De La Peña adjusts the dose in diabetic patients and instructs them to monitor glucose for “usually the first three to five days”, whether they use insulin or oral agents.
Where control is tight, she involves the endocrinologist to adjust medication “just for that amount of time, until the peak of the steroid stabilises the glucose.” The adjustment is temporary and the effect resolves.
Post-dural-puncture headache
A characteristic headache: clearly worse sitting or standing, clearly better lying flat. It follows a leak of cerebrospinal fluid.
It can occur even when the procedure appeared correct. As De La Peña explains, the spread can look right and aspiration can be negative, yet the dura may have been tented without notice, producing a micro-leak.
Management is staged. First, conservative care — hydration, NSAIDs and rest, with reassurance that it is transient. If after two or three days it has not improved or is worsening, the treatment is an epidural blood patch: roughly 20 mL of the patient's own blood injected into the epidural space, where it clots and seals the leak. Relief typically arrives the same or next day.
Epidural haematoma — the emergency behind the anticoagulation question
This is why the medication history is taken as seriously as it is.
Bleeding into the epidural space compresses the cord or the cauda equina. De La Peña lists the agents now routinely encountered in practice — aspirin, apixaban, rivaroxaban, edoxaban — noting that all of them raise the risk when performing neuraxial blocks.
The governing reference is ASRA, the American Society of Regional Anesthesia and Pain Medicine, which publishes how many days each anticoagulant must be held before a neuraxial block and when it may be resumed afterwards. Those intervals are drug-specific and are not a matter of clinical preference.
Presentation: new motor or sensory deficit, escalating back pain, or cauda equina symptoms — saddle numbness, bladder or bowel dysfunction. Any of these after an epidural injection requires urgent MRI. The window in which decompression preserves function is short.
Infection, abscess and the progression that is preventable
De La Peña's position is that infection is the complication most clearly within the clinician's control: “infection can be prevented. Sterile technique is the most important to prevent it.”
Higher-risk patients she identifies as diabetic, immunosuppressed, and known MRSA carriers.
The progression matters for patients as well as clinicians. A superficial skin infection that is not treated properly can extend deeper, producing epidural abscess, discitis or osteomyelitis. That is why redness spreading at the injection site, or fever and chills in the days afterwards, is not something to wait out.
Note that abscess and haematoma present similarly — both produce neurological deficit — and both are investigated with MRI.
Intrathecal injection and arachnoiditis
The reason the confirmation sequence exists. If the dura is penetrated and steroid delivered into the intrathecal space rather than the epidural space, the consequences De La Peña names are arachnoiditis and nerve damage.
Three steps guard against it: loss of resistance to identify the space, aspiration to confirm no blood or cerebrospinal fluid returns, and contrast under fluoroscopy to confirm the spread. Her verdict on the last is unambiguous — contrast “is extremely important to avoid complications.”
Why the steroid itself carries a risk decision
Particulate steroids form a suspension. They last longer, and they can occlude a small artery.
De La Peña ranks them from most to least particulate — methylprednisolone, triamcinolone, betamethasone — and states the tradeoff directly: longer duration, “but at the same time they have a higher risk of complications.”
Non-particulate dexamethasone dissolves completely, carrying “less risk of embolization and cause of arachnoiditis or nerve damage”, at the cost of a shorter duration of action. Because the neural foramen carries radicular arteries, non-particulate steroid is preferred for transforaminal injections specifically.
Longer-term steroid effects
De La Peña's framing is that the systemic effects associated with steroids — bone density loss, adrenal suppression and the rest — are “usually more common with patients that have systemic steroids, meaning oral steroids”, rather than with intermittent epidural injections.
That is not a reason to treat epidural steroid as consequence-free. It is the reason injections are spaced and limited in number rather than repeated on demand.
When to seek help
| Symptom | What it may be | Act |
|---|---|---|
| New leg weakness, foot drop | Haematoma or abscess | Same day, urgent |
| Bladder or bowel change, saddle numbness | Cauda equina compression | Emergency |
| Fever, chills, spreading redness | Infection | Same day |
| Headache worse upright, better flat | Dural puncture | Call; conservative first, blood patch if persisting |
| Sore back, flushing, hiccups, poor sleep | Expected steroid effects | Self-limiting |
| Raised blood glucose for 3 to 5 days | Expected rebound hyperglycaemia | Monitor; adjust with your physician |
Learn blocks with your hands, not from a page
Empire’s Pain Management Training (THE Pain Show) is accredited for 25.25 AMA PRA Category 1 Credits™, jointly provided by AKH, Inc, and Empire Medical Training. For narrower peripheral work, Joint, Extremity and Non-Spinal Injection Training carries 6.75 credits for the complete in-person hybrid program, and Advanced Musculoskeletal Ultrasound Guided Injections builds the guidance skills above.
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